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Vomiting, diarrhea and stomach cramps, oh my! It starts when you feel a little under the weather, maybe some body aches and fatigue. Then you might start to run a fever. “Do I have the flu?” you ask yourself. Then maybe you lie down to rest for a while. But then, faster than you can say “barf bag,” you can’t make it to the bathroom soon enough.

As the hours and days of misery pass with you lying on the couch thinking about anything other than food, you contemplate between visits to the bathroom: What was it that made me sick? Is this just the stomach flu? That nasty 24-hour bug everyone’s had? Or is this food poisoning?

What is food poisoning? How is it different than the stomach flu?

Guess what: There are no real medical diseases called “food poisoning” or “stomach flu.” There is no disease called “the 24-hour flu.” These are just common terms to describe a myriad of illnesses that all have very similar symptoms: vomiting and/or diarrhea, maybe with stomach pain, fever and body aches. This cluster of illnesses is sometimes called enteric diseases because they affect your intestines. They are also sometimes called foodborne diseases. They are not related to influenza, and the seasonal flu shot does not protect against these diseases, according to the Centers for Disease Control and Prevention.

The CDC estimates that there are around 48 million people in the U.S. each year who get sick from foodborne diseases, with 128,000 hospitalizations and 3,000 deaths. That means that 1 in 6 Americans gets sick from something they ate each year.

According to foodsafety.gov, these are some of the nasty bugs that cause illnesses sometimes referred to as food poisoning or stomach flu: Norovirus, Rotavirus, Salmonella, Shigella, Campylobacter, Escherichia coli, Clostridium difficile, Staphylococcus aureus, Bacillus cereus, Giardia and Cryptosporidium.

Here are some myths and facts about food poisoning:

Myth No. 1: It had to be something I ate.

Fact: Bacteria, viruses and parasites that are spread through food can be spread other ways, too.

The details: Despite being frequently called foodborne diseases, these enteric pathogens are really good at getting from one person to another. They are almost always spread through the fecal-oral route, which means you have to swallow fecal matter to get sick (gross!). Often, that happens when you consume food or water that has been contaminated with the pathogen.

But they can also be spread from direct or indirect contact with animals that carry the germs, or contact with another person who was sick. So, germ particles get on your hands, then they are transferred to your mouth.

And often a germ is spread to one person in one way — say, through food — then transferred to other people directly (person-to-person). Really, they’ll get into your belly any way they can.

Myth No. 2: I know I got sick from the chicken (or the taco or the take-out) because I started feeling sick right after I ate it.

Fact: Many diseases spread through food strike days or weeks after you eat it.

The details: Most of the time, the last thing you ate wasn’t what made you sick. Many foodborne diseases don’t start to produce the toxins that make you sick until after they are in your intestines. Then, it can take some time (days or weeks, sometimes) before enough of the toxin is built up to cause the symptoms.

But keep in mind that there are some foodborne pathogens that do produce toxins in food that has been sitting out unrefrigerated. These make people sick more quickly than the bugs that produce toxins after being ingested. But since so many of these foodborne diseases cause similar illnesses, you can’t tell what germ made you sick just by the symptoms. Only a laboratory test of your stool can tell you what germ made you sick. Thus, you can't tell for sure when you ate food that made you sick.

Myth No. 3: I had a different disease than someone else I know who was sick because I was much more ill.

Fact: Germs can affect people in different ways.

The details: The same bug can result in different illnesses in different people. The people most severely affected by these germs are the elderly, the very young, pregnant women, and people who have weak immune systems, like people with cancer or AIDS, according to the U.S. Food and Drug Administration.

Just because your symptoms were much more mild than someone else’s doesn’t mean it was a different disease. You really can’t tell what particular bug made you sick just by the symptoms. Remember that only a laboratory test through your doctor can tell you for sure what made you sick.

Myth No. 4: It couldn’t have been the mashed potatoes (or turkey or gravy) because everyone ate that but I was the only one who got sick.

Fact: Sometimes only one person gets sick after eating a shared food item that was contaminated.

The details: Most of the time you cannot tell what it was that made you sick. Remember: It might not have even been the food that made you sick. You might have gotten it some other way. But let’s say that somehow we know for sure the germ that made you sick came from food. Well, sometimes more than one person can eat the same contaminated food and only one person will get sick. Or one person gets much sicker than someone else (see Myth No. 3). There are lots of reasons for this.

Maybe the person who got sick was fighting off a different illness or was felling stressed or tired, so his or her germ-fighting immune system wasn’t up to par. At the same time, maybe everyone else did swallow the germs, but their immune systems fought it off before the germs made them sick.

Maybe the people who didn’t get sick actually were sick with a bout or two of diarrhea but didn’t think to mention it. (A lot of people focus on the vomiting and forget or are embarrassed to mention anything about diarrhea.)

Or maybe there was a pocket of food that was more heavily contaminated, and the person who got sick drew the “unlucky” card.

Myth No. 5: I was the only one who ate the enchilada (or the hamburger or the milkshake), so it had to be that.

Fact: Most of the time, you can’t tell what it was that made you sick.

The details: In reality, no one can tell for sure what it was that made one person sick. We can get some really good guesses based on risk factors that people may have been exposed to. These might be eating raw or undercooked meat, drinking raw milk, eating raw cookie dough or eating something that was clearly rotten or contaminated. There are also many well-known non-food ways to get these germs: from another person, by drinking or swimming in lake water, from pet food, and from contact with animals like live poultry or reptiles (see cdc.org). But unless there is more evidence to prove that guess, it remains a guess.

Public health officials called epidemiologists and other public health professionals routinely track and investigate foodborne diseases. It is an evolving science, according to the CDC, which combines a solid understanding of disease transmission, exciting and innovative laboratory methods, traditional person-tracking, in-depth interviews with people who were diagnosed with certain diseases, statistical comparisons of risk factors reported by sick people, and effective coordination between regulatory agencies. As a result, in recent years epidemiologists have identified a plethora of sources of foodborne illness that were previously undetected, like sprouted chia powder, sesame paste, spinach and more, according to the CDC's website.

The bottom line

Here are some of foodsafety.gov's best ways to prevent getting sick from something you ate:

Wash your hands frequently and thoroughly, especially after using the restroom and before every meal.

Cook food all the way, especially chicken, hamburger, eggs and other foods of animal origin. Use a meat thermometer to be sure.

Do not consume raw milk or products made from raw milk. This is especially important for people most at-risk for serious complications: the very young, the elderly, pregnant women and those with weak immune systems.

Keep hot foods hot and cold foods cold. Store foods immediately after the meal is finished, or within two hours.

And if you have diarrhea or vomiting:

Do not prepare food for other people.

See your doctor.

Marilee Kellis is an epidemiologist and has worked in public health for the better part of a decade.